GrapheneOS I think everyone understood these phones would probably reach end of life when Google said they would. People are just griping a little. It's reasonable to gripe when Google is being so unreasonable in how they support devices (devices with the identical chipset, so the usual excuse of not having the drivers from Qualcomm doesn't apply).
People were also just hoping that it might be different with these particular devices, because, again, despite being from different model years they (unusually) had the same chipset and are basically identical in terms of internal components. Indeed, for a long time the GrapheneOS install guide itself, under recommended devices, suggested this might happen with the Pixel 5 and 4a5G. So it was hardly only a few people on the forum that thought this.
I do think it is a false economy to assume that it's alway a better deal to buy a new phone with longer support. I bought a 4a5G a year ago for $134. It would take many years of phones at that sort of price, to equal the cost of a Pixel 8. In the mean time, the money saved can earn interest (if one is diligent about such things). There is a time value to money (something most people really don't understand or take into account). At a given cost, it is much more expensive to buy something in the present, than in the future. Of course, if one just keeps skipping from cheap phones, with a year or two of updates left, to the next, one does have to put up with the hassle of switching phones.
In addition, a lot of people are skeptical as to whether or not Google will make good on it's promise to support the Pixel 8 for seven years. That's a long time and Google has a habit of breaking promises. In seven years time I wouldn't be suprised if Google has dropped the Pixel line altogether. Remember the beloved Nexus phones?
So I'd say for $200 or less, a Pixel 6 right now is a good deal. But the Pixel 8 is not a good deal, both in terms of the time value of money and because there are too many future unknowns. Unfortunately, because of the reception issues, the Pixel 6 is not a great phone, so choices are kind of bleak right now, for people wanting or needing to save money.